The invention relates to an improved cutting element substrate having a cant intersecting a first and second interfacial surface. More particularly, the invention relates to cutting element substrates with non-planar, non-linear interfaces with an abrasive layer of super hard material affixed thereto often using a high pressure high temperature press apparatus. Cutting elements are useful as cutting inserts in drilling bits such as roller cone bits, rotary fixed cutter bits, earth boring bits, percussion bits or impact bits, and drag bits. Sometimes the cutting elements or inserts are defined by their geometric placement on a drill bit and by type of drill bit used. Some examples are heel and gage inserts. The cutting elements installed on a drill bit or other tool are used for earth or rock boring, such as may occur in the drilling or enlarging of an oil, gas, geothermal or other subterranean borehole, and to bits and tools so equipped. Additionally, other downhole tools are employed to cut or enlarge a borehole or which may employ superabrasive cutting elements or inserts. For example, such tools might include reamers, fishing tools, stabilizers, tool joints, wear knots and steering tools. There are also formation cutting tools employed in subterranean mining, such as drills and boring tools.
A typical rolling cone bit operates by the use of three rotatable cones oriented substantially transversely to the bit axis in a triangular arrangement, with the narrow cone ends facing a point in the center of the triangle which they form. The cones have cutting elements or inserts formed or placed on their surfaces. Rolling of the cones in use due to rotation of the bit about its axis causes the cutters to embed into hard rock formations and remove formation material by a crushing action. Percussion bits are used with boring apparatus known in the art that moves through a geologic formation by a series of successive impacts against the formation, causing a breaking and loosening of the material of the formation. Drilling bits are used to bore through a variety of geologic formations for oil, gas, and geothermal well exploration. A drag bit or fixed-cutter bit is designed to be turned in a clockwise direction (looking downward at a bit being used in a hole, or counterclockwise if looking at the bit from its cutting end about its longitudinal axis) about its longitudinal axis.
A cutting element, Polycrystalline Diamond Cutter(PDC) or an insert, typically has super hard material layer or table formed under high temperature and pressure conditions, usually in a press apparatus designed to create such conditions, to a cemented carbide substrate (such as cemented tungsten carbide) containing a metal binder or catalyst such as cobalt. The substrate is often less hard than the superhard material to which it is bound. Some examples of superhard materials that high temperature high pressure (HPHT) presses may produce and sinter include cemented ceramics, diamond, polycrystalline diamond, and cubic boron nitride. The cutting element may be mounted to a drill bit either by press-fitting or otherwise locking the substrate into a receptacle on a steel-body drag bit, or by brazing the cutter substrate directly into a preformed pocket, socket or other receptacle on the face of a bit body.
A cutting element or insert is normally fabricated by placing a cemented carbide substrate into a container or cartridge with a layer of diamond crystals or grains loaded into the cartridge adjacent one face of the substrate. A number of such cartridges are typically loaded into a reaction cell and placed in a high pressure high temperature press apparatus. The substrates and adjacent diamond crystal layers are then compressed under HPHT conditions which promotes a sintering of the diamond grains to form the polycrystalline diamond structure. As a result, the diamond grains become mutually bonded to form a diamond table over the substrate face, which is also bonded to the substrate face.
Cutting elements are subject to intense forces, torques, vibration, high temperatures and temperature differentials during drilling and borehole formation. Drill bit stresses may be further aggravated by drilling anomalies during well bore formation such as bit whirl, spalling, delamination, or fracture of the abrasive layer or substrate often occurs thereby reducing or eliminating the cutting elements efficacy and decreasing overall drill bit wear life. The diamond layer of a cutting element sometimes delaminates from the carbide substrate after the sintering process and during percussive and abrasive use.
Damage typically found in these percussive and drag bits is a result of shear failures, although non-shear mode of failure are not uncommon. The interface between the diamond and substrate is particularly susceptible to non-shear failure modes. The failures may be mitigated by eliminating failure initiation points at the diamond-substrate interface.